We recently moved into a new home. The front porch appeared to have muddy tracks on it which we assumed could be easily washed off with detergent and water. After unsuccessfully attempting to clean it, I learned from the worker who poured the concrete that workers had walked on the fresh concrete with muddy boots on. What is the best way to remove these stains without causing any pitting or other problems?

If the mud is embedded in the surface about the only way to "clean" it will be a power wash. It will "etch" the surface and then you'll need to reseal it. And it will most likely have a rougher surface than before. Pics may help us with better advice.

This was new construction, and I believe the builder will take responsibility for the problem. I wanted to get your input, because the foreman suggested power washing, but the man who poured the concrete says that power washing can cause pitting if not done carefully. He suggested trying a wire brush.

While I agree with scrubbing, a wire brush often leaves black marks on the concrete and any leftover steel fragments will rust. Pressure washing done correctly shouldn't harm sound concrete although it's not a good idea to use the zero [red] tip.

I have to agree with Marksr. Careful power washing will do a god job.
And I might add that looks pretty bad. I'm surprised they let that go. Why in heck would a guy walk on fresh concrete?
Assuming the contractor makes good on it (and I believe he will) be sure to ask him about sealing it after the power wash. Silkin's (sp?) makes a superior product as opposed to Thompso's in this case. But I'm not sure if its available everywhere.